The following changes since commit 82af46be1fa0c0e188bbb6723008fa33a510606f:
lfsr: ensure that the cycle follows the randrepeat= setting (2012-12-04 13:12:25 +0100)
are available in the git repository at:
git://git.kernel.dk/fio.git master
Jens Axboe (2):
lfsr: add HOWTO and man page documentation
Fix man page indentation
HOWTO | 17 +++++++++++++++++
fio.1 | 22 +++++++++++++++++++++-
2 files changed, 38 insertions(+), 1 deletions(-)
---
Diff of recent changes:
diff --git a/HOWTO b/HOWTO
index 32e5d66..6d541af 100644
--- a/HOWTO
+++ b/HOWTO
@@ -753,6 +753,23 @@ softrandommap=bool See norandommap. If fio runs with the random block map
will not be as complete as with random maps, this option is
disabled by default.
+random_generator=str Fio supports the following engines for generating
+ IO offsets for random IO:
+
+ tausworthe Strong 2^88 cycle random number generator
+ lfsr Linear feedback shift register generator
+
+ Tausworthe is a strong random number generator, but it
+ requires tracking on the side if we want to ensure that
+ blocks are only read or written once. LFSR guarantees
+ that we never generate the same offset twice, and it's
+ also less computationally expensive. It's not a true
+ random generator, however, though for IO purposes it's
+ typically good enough. LFSR only works with single
+ block sizes, not with workloads that use multiple block
+ sizes. If used with such a workload, fio may read or write
+ some blocks multiple times.
+
nice=int Run the job with the given nice value. See man nice(2).
prio=int Set the io priority value of this job. Linux limits us to
diff --git a/fio.1 b/fio.1
index 2db9793..26a4650 100644
--- a/fio.1
+++ b/fio.1
@@ -486,8 +486,8 @@ transfer as fio ioengine
.B e4defrag
IO engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate defragment activity
request to DDIR_WRITE event
-.TP
.RE
+.P
.RE
.TP
.BI iodepth \fR=\fPint
@@ -617,6 +617,26 @@ fails to allocate the map, if this option is set it will continue without a
random block map. As coverage will not be as complete as with random maps, this
option is disabled by default.
.TP
+.BI random_generator \fR=\fPstr
+Fio supports the following engines for generating IO offsets for random IO:
+.RS
+.TP
+.B tausworthe
+Strong 2^88 cycle random number generator
+.TP
+.B lfsr
+Linear feedback shift register generator
+.TP
+.RE
+.P
+Tausworthe is a strong random number generator, but it requires tracking on the
+side if we want to ensure that blocks are only read or written once. LFSR
+guarantees that we never generate the same offset twice, and it's also less
+computationally expensive. It's not a true random generator, however, though
+for IO purposes it's typically good enough. LFSR only works with single block
+sizes, not with workloads that use multiple block sizes. If used with such a
+workload, fio may read or write some blocks multiple times.
+.TP
.BI nice \fR=\fPint
Run job with given nice value. See \fInice\fR\|(2).
.TP
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